Efficient Single-Photon Isotope Separation

Physical Sciences : Physics

Available for licensing


  • Mark Raizen, Ph.D. , Physics
  • Melissa Jerkins , Physics
  • Bruce Klappauf, Ph.D. , University of Texas at Austin
  • James Lawler , University of Wisconsin - Madison
  • Isaac Chavez , Physics
  • Uzi Even, Ph.D.

Background/unmet need

Isotope separation is one of the grand challenges of modern society and holds great potential for basic science, and medicine. The long-standing efforts to separate isotopes date back to the 1930s and fall into several categories. Two standard methods of separation are gaseous diffusion and the ultra-centrifuge. These methods require many stages of enrichment and are very inefficient. Furthermore, these methods are only economically feasible for a few elements that can be kept in gas phase. Isotope separation is also accomplished with mass spectrometry. This method has high isotopic selectivity due to the use of a quadrupole mass filter, but it is also very inefficient.

In recent years, the method of isotope separation by laser ionization was developed. This approach is highly selective but requires multiple (typically three) high-powered lasers for efficient ionization. With this background, it is clear that there is an urgent need for a new and efficient method of isotope separation.

Invention Description

Inventors at The University of Texas at Austin have developed a new and general approach to isotope separation. The method is based on an irreversible change of the mass-to-magnetic moment ratio of a particular isotope in an atomic beam, followed by guiding in a magnetic field. The underlying mechanism is a reduction of the entropy of the beam by the information of a single-scattered photon for each atom that is separated.

This method is closely tied to the concept of Maxwell’s Demon, a thought experiment first proposed by James Clerk Maxwell in 1871. Subsequent work by Leo Szilard in 1929 showed that the Demon works by extracting information as a way of lowering the system entropy without violating the second law of thermodynamics. The new method is simulated numerically for a range of examples.


  • Uses only a single, low-power, laser excitation source
  • Relies on mass-to-magnetic moment ratio
  • Low-cost permanent magnets can be used for guiding

Market potential/applications

The primary market for this technology is the use of enriched isotopes in medicine. Another market is basic research.

Development Stage

Proof of concept

IP Status

  • 2 foreign patents application filed
  • 2 foreign patents issued
  • 1 U.S. patent issued: 8,672,138
  • 1 U.S. patent issued: 8,975,810